On V-engines, which have two cylinder banks, every cylinder in one of the banks may misfire, which may be referred to as cylinder bank misfire. Additionally, individual cylinders of the engine may misfire.
Responsive to misfire, the misfiring cylinders may be deactivated until the engine is serviced. For example, if an individual cylinder repeatedly misfires, it may be deactivated by discontinuing fuel injection until the engine is serviced. As another example, if a bank of cylinders experiences misfire, all cylinders in the bank may be deactivated in a similar way, again until the engine is serviced.
However, the inventors herein have recognized a disadvantage with the above approach. Namely, cylinder bank misfire may be due to significantly different causes than individual cylinder misfire. Particularly, cylinder bank misfire may not be persistent misfire and may be due to a temporary cause, such as charge air cooler condensate ingestion by the engine, whereas individual cylinder misfire may be due to degraded wiring, a degraded spark plug for that cylinder, etc.
The inventors herein have recognized problems described above and have devised an approach to at least partially address them. Thus, in one example, a method for deactivating and reactivating a cylinder bank in a V-engine is disclosed. The method comprises, responsive to cylinder bank misfire detection, reactivating cylinders sequentially based on misfire detection upon reactivation of a cylinder.
For example, each cylinder within a cylinder bank may be deactivated responsive to misfire occurring in a number of different cylinders, for example all the cylinders, of the bank. Then, during continued engine operation while remaining cylinders continue to combust, the deactivated cylinders are sequentially reactivated, for example one at a time. Upon activation of each cylinder, individual cylinder misfire is monitored for that reactivated cylinder. If no misfire is detected, the next cylinder in the bank may be activated, and again monitored for misfire.
In this way, it can be advantageous to reactivate the cylinders in order to reduce degraded vehicle performance and return to all cylinders firing operation.
In such an approach, cylinder bank misfire detection may be based on crankshaft acceleration and exhaust air fuel ratio, for example. As noted above, the cylinder bank may be deactivated responsive to the detection of misfire and then sequentially reactivated. By sequentially reactivating the cylinders, the cylinder bank may be reactivated over time such that degradation of the system is reduced while a duration in which engine and/or vehicle performance may be degraded is reduced.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
For example, while in one example distinctions are made between cylinder bank misfire and individual cylinder misfire, the approaches described herein may be applied to respond to misfire differently depending on the number of cylinders experiencing misfire. For example, distinctions may be made between misfire in a group of identified cylinders, and misfire in an individual cylinder within the group. For example, another embodiment may include a method for deactivating and reactivating a cylinder group of a plurality of cylinders in an engine. The method may include, responsive to misfire in a plurality of cylinders in the group, deactivating the cylinder group (while continuing combustion in remaining engine cylinders). Further, the method may include reactivating deactivated cylinders sequentially based on whether or not individual cylinder misfire is identified upon reactivation of each cylinder in the group until all cylinders are reactivated. If upon reactivation individual cylinder misfire is detected, then that cylinder may be deactivated with remaining cylinders in the group being reactivated. Further, the method may include monitoring individual cylinder misfire during engine operation and deactivated only if the identified cylinder with individual cylinder misfires.